Extraction Of Alumina From Oil Shale Ash And Its Application

Oil shale ash is the residue of the retorting or burning of oil shale. A great quantity of oil shale ash not only occupied land, but also results in serious environmental pollution. Meanwhile, this will limited the utilization and development of oil shale industry. Therefore, it is significant to find a feasible and reasonable treatment of oil shale ash.In this paper, we adhered to the principle of comprehensive utilization of oil shale ash, proposing a series of method for comprehensive utilization of oil shale ash. In detail, firstly the extraction of alumina from oil shale ash was researched; secondly, the precursor of alumina was treated by combined dispersion (surfactant, ultrasonics, and azeotropic distillation) to prepare nano alumina; to improve further the added value of oil shale ash, the alumina was modified with chitosan to synthesize functional alumina hybrid adsorbent. Addtionally, the adsorption behavior of heavy metals and phenolic compounds on alumina hybrid adsorbent were investigated. The main conclusions are as follows.1. The extraction of alumina from oil shale ash was originally researched and the optimum parameters were determined. The experiments results show that the purity percent is 98.87～99.4% and the extraction percent is 76.08～79.86%, under optimal conditions (temperature 750℃, calnations time 2-3h and so on).2. The preparation of nano alumina from oil shale ash was researched. Also, the dispersion mechanism was discussed. The results show that the combined method of surface modification, ultrasonic oscillation, and azeotropic distillization could prevent the agglomeration of precursor of alumina. On the other hand, this method can prevent the second agglomeration of alumina during the calcination. The effection of mixed surfactant (PEG6000:PEG10000:PEG20000 1:1:1) is better than one. High flow rate of carbon dioxide result in the agglomeration of alumina and big particle size. The optimum flow rate is 5 mL/min, and the particle size of obtained alumina is less than 100 nm.3 The shell corsslinked alumina-chitosan hybrid adsorbent was prepared. In detail, the alumina was used as matrix of adsorbents. The malonate was used as bridge between the alumina and chitosan. The sodium polyphosphate was crosslinking reagent. The BET results show that the specific surface area is 225.31 m2/g, the volume of pore is 0.473 cm3/g, the pore diameter is 8.4 nm, the pore type is ink bottle. The pores exist in 4.8 nm and 3.5 nm. The pore of adsorbent is mesoporous. The chitosan percent of this sorbent is 12.86 wt.%.4. The adsorption behavior of phenol on Al2O3-CCS was investigated. The results show that the adsorbent has the maximum equilibrium adsorption capacity at pH 7.0, than pH 9.0 and low pH value. Initial concentration of phenol has on the adsorption capacity of Al2O3-CCS beads. With the increase of initial concentration, the adsorption capacity increased. The adsorption efficiency of phenol is high when the adsorbent was used in low initial concentration of phenol. Additionally, with the shaking time increasing, the relative recovery of phenol was also increased. The regeneration and reusability of Al2O3-CCS improve that the sorbent can be used to removal phenol from contaminated water. The Langmuir model and Freundlich model was used to analyze the data. The results of calculation reveal that:the adsorption behavior of phenol on Al2O3 was in basic agreements with single-layer adsorption model. It also been determined that the saturated adsorption capacity of phenol were 89.21 mg/g (pH=5.0),139.86 mg/g (pH=7.0),91.41 mg/g (pH=9.0), respectively.5. The adsorption behavior of Copper(II) on Al2O3-CCS was investigated. The results show that the adsorbent has the maximum equilibrium adsorption capacity at pH 2.5, than pH 5.0 and 7.0. Initial concentration of Cu(II) has on the adsorption capacity of Al2O3-CCS beads. With the increase of initial concentration, the adsorption capacity increased. The adsorption efficiency of Cu(II) is high when the adsorbent was used in low initial concentration of Cu(II). Additionally, with the shaking time increasing, the relative recovery of Cu(II) was also increased. The regeneration and reusability of Al2O3-CCS improve that the sorbent can be used to removal Cu(II) from contaminated water. The Langmuir model and Freundlich model was used to analyze the data. The results of calculation reveal that:the adsorption behavior of Cu(II) on Al2O3 was in basic agreements with single-layer adsorption model. It also been determined that the saturated adsorption capacity of Cu(II) were 315.46mg/g (pH=2.5),292.40mg/g (pH=5.0),106.95 mg/g (pH=7.0), respectively.